Refrigeration apparatus

ABSTRACT

Disclosed is an apparatus that provides refrigerant based energy storage and cooling. When connected to a condensing unit, the system has the ability to store energy capacity during one time period and provide cooling from the stored energy during a second time period. The system requires minimal energy to operate during either time period, and only a fraction of the energy required to operate the system during the first time period is required to operate the system during the second time period using an optional refrigerant pump.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 10/967,114 entitled “Refrigeration Apparatus” by RamachandranNarayanamurthy et al., filed Oct. 15, 2004, which claims the benefit ofand priority to U.S. provisional application No. 60/511,952, entitled“Refrigerant Based High Efficiency Energy Storage and Cooling System”,filed Oct. 15, 2003. The entire contents of the above listedapplications are hereby specifically incorporated herein by referencefor all they disclose and teach.

BACKGROUND OF THE INVENTION

With the increasing demands on peak power consumption, ice storage is anenvironmentally benign method that has been utilized to shift airconditioning power loads to off-peak times and rates. A need exists notonly for load shifting from peak to off-peak periods, but also forincreases in air conditioning unit capacity and efficiency. Current airconditioning units having energy storage systems have had limitedsuccess due to several deficiencies including reliance on waterchillers, that are practical only in large commercial buildings, andhave difficulty achieving high-efficiency. In order to commercializeadvantages of thermal energy storage in large and small commercialbuildings, thermal energy storage systems must have minimalmanufacturing and engineering costs, maintain maximum efficiency undervarying operating conditions, demonstrate simplicity in the refrigerantmanagement design, and maintain flexibility in multiple refrigeration orair conditioning applications.

Systems for providing stored energy have been previously contemplated inU.S. Pat. No. 4,735,064, U.S. Pat. No. 4,916,916 both issued to HarryFischer and to U.S. Pat. No. 5,647,225 issued to Fischer et al. All ofthese patents utilize ice storage to shift air conditioning loads fromon-peak to off-peak electric rates to provide economic justification andare hereby specifically incorporated by reference for all they teach anddisclose.

SUMMARY OF THE INVENTION

An embodiment of the present invention may therefore comprise arefrigeration apparatus comprising: a condensing unit comprising acompressor and a condenser; a thermal energy storage unit comprising atank that contains a storage heat exchanger and at least partiallyfilled with a phase change liquid; a load heat exchanger; arefrigeration management unit connected to the condensing unit, thethermal energy storage unit and the load heat exchanger; and, arefrigerant management controller in communication with therefrigeration management unit and comprised of operational controllersusing environmental data to regulate and control operation of therefrigeration apparatus.

The disclosed embodiments offer the advantage of using power fromelectric utility companies during low demand, off-peak hours, which areusually at night, when these companies use their most efficientequipment. For example, high efficiency electric generators, typicallystream-driven, produce a kilowatt-hour (KWH) for approximately 8,900BTU. In contrast, a peak hour high capacity electrical generator, suchas a gas turbine, can use as much as 14,000 BTU to produce the same KWHof electricity. Second, the transmission lines also run cooler at nightresulting in higher efficiency of energy usage. Finally, for air-cooledair-conditioning systems, operating the system at night affords a higherefficiency by lowering the temperature of the condensing unit.

The disclosed refrigerant-based energy storage and cooling system hasthe advantage of operating at high efficiency providing an overallsystem that shifts power usage without significant total energy lossesand with the increased efficiencies of off-peak power generation andoff-peak compressor-based refrigerant cooling, a net reduction in thetotal energy consumption of an individual operating unit.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings,

FIG. 1 illustrates an embodiment of a high efficiency refrigerant coldstorage and cooling system in a mode used for cooling a process fluid.

FIG. 2 illustrates an embodiment of a high efficiency refrigerant coldstorage and cooling system in a configuration for air conditioning withmultiple evaporators.

FIG. 3 is a table illustrating the component status for an embodiment ofa high efficiency refrigerant cold storage and cooling system.

FIG. 4 is an embodiment of a refrigeration apparatus that providesenergy storage and cooling.

DETAILED DESCRIPTION OF THE INVENTION

While this invention is susceptible to embodiments in many differentforms, there is shown in the drawings and will be described herein, indetail, specific embodiments thereof with the understanding that thepresent disclosure is to be considered as an exemplification of theprinciples of the invention and is not to be limited to the specificembodiments described.

FIG. 1 illustrates an embodiment of a high efficiency refrigerant coldstorage and cooling system. The described embodiments minimizeadditional components and use nearly no energy beyond that used by thecondensing unit to store the energy. The refrigerant cold storage designhas been engineered to provide flexibility so that it is practicable fora variety of applications. The embodiments can utilize stored energy toprovide chilled water for large commercial applications or providedirect refrigerant air conditioning to multiple evaporators. The designincorporates multiple operating modes, the ability to add optionalcomponents, and the integration of smart controls that allow energy tobe stored and released at maximum efficiency. When connected to acondensing unit, the system stores refrigeration energy in a first timeperiod, and utilizes the stored energy during a second time period toprovide cooling. In addition, both the condensing unit and therefrigerant cold storage system can operate simultaneously to providecooling during a third time period.

As shown in FIG. 1, an embodiment of a high efficiency refrigerantenergy storage and cooling system is depicted with four major componentsincorporated in the system. The air conditioner unit 102 is aconventional condensing unit that utilizes a compressor 110 and acondenser 111 to produce high-pressure liquid refrigerant deliveredthrough a high-pressure liquid supply line 112 to the refrigerationmanagement unit 104. The refrigeration management unit 104 is connectedto an energy storage unit 106 comprising an insulated tank 140 withice-making coils 142 and is filled with a phase change liquid such aswater or other eutectic material. The air conditioner unit 102, therefrigeration management unit 104 and the energy storage assembly 106act in concert to provide efficient cooling to the load heat exchanger108 (indoor cooling coil assembly) and thereby perform the functions ofthe principal modes of operation of the system.

As further illustrated in FIG. 1, the compressor 110 produceshigh-pressure liquid refrigerant delivered through a high-pressureliquid supply line 112 to the refrigeration management unit 104. Thehigh-pressure liquid supply line 112 is split and feeds an oilstill/surge vessel 116 and a pressure operated slide valve 118. Thestill/surge vessel 116 is used to concentrate the oil in thelow-pressure refrigerant and return it to the compressor 110 through thedry suction return 114. Without the still/surge vessel 116, some oilwould remain in the accumulator vessel, ultimately causing thecompressor 110 to seize due to lack of oil, and the heat exchangers tobecome less effective due to fouling. The vapor rises to the top of thestill/surge vessel 116 and out vent capillary 128, to be re-introducedin the wet suction return 124. This is done to encourage vapor flow outof the heat exchanger within the still/surge vessel 116, and in thepreferred direction. The length of the vent capillary 128 or similarregulated bleed device is used to control the pressure in thestill/surge vessel 116, and hence, the boil rate and the volume ofrefrigerant in the system. The pressure operated slide valve 118 alsoallows a secondary supply of high-pressure liquid refrigerant that canbypass of the rest of the refrigerant management system 104 and suppliesliquid refrigerant to a liquid refrigerant pump 120 and directly to theload unit 108.

When activated, a liquid refrigerant pump 120 supplies the evaporatorcoils of the load heat exchanger 122 within the load portion 108 of theenergy storage and cooling system with liquid refrigerant. Low-pressurerefrigerant returns from the evaporator coils of the load heat exchanger122 via wet suction return 124 to an accumulator or universalrefrigerant management vessel (URMV) 146 and to the internal heatexchanger composed of ice freezing/discharging coils 142. Thelow-pressure vapor exits from the top of the URMV 146 and returns to theair conditioning unit 102 through dry suction return 114 along with thedistilled oil enriched refrigerant flowing out of the bottom of the oilstill/surge vessel 116 through an oil return capillary 148. The oilreturn capillary 148 controls the rate at which the oil is re-introducedinto the system. Oil enriched liquid refrigerant passes through a P-trap150, which eliminates (blocks) an undesired path for refrigerant shouldthe still/surge vessel 116 become empty.

Additionally, the wet suction return 124 connects with a bifurcator 130prior to the URMV 146. The bifurcator supplies low-pressure refrigerantfrom the mixed phase regulator 132 (TRVT). The mixed phase regulator 132meters the flow of refrigerant within the system by incorporating avalve (orifice) that opens to release mixed phase refrigerant, only whenthere is sufficient quantity of liquid built up in the condenser 111. Inthis way, the compressor 110 driving the system needs merely to operateto feed high pressure refrigerant, which can be matched to the coolingload. This mixed phase regulator 132 prevents vapor bleeding into thelow-pressure side (heat load portion) of the system and virtuallyeliminates vapor feed to the URMV 146 from the compressor 110, whilealso dropping the required pressure from the condenser pressure to theevaporator saturation pressure. This results in greater overallefficiency of the system while simplifying the liquid overfeedcharacteristics of the refrigerant management unit.

The insulated tank 140 contains dual-purpose ice freezing/dischargingcoils 142 (nominally geometrically designed helical coils), arranged forgravity circulation and drainage of liquid refrigerant, and areconnected to an upper header assembly 154 at the top, and to a lowerheader assembly 156 at the bottom. The upper header assembly 154 extendsoutward through the insulated tank 140 to the refrigeration managementunit 104. When refrigerant flows through the ice freezing/dischargingcoils 142 and header assemblies 154 and 156, the coils act as anevaporator and the fluid 152 solidifies in the insulated tank 140 duringone time period. The ice freezing/discharging coils 142 and headerassemblies 154 and 156 are connected to the low-pressure side of therefrigerant circuitry and are arranged for gravity or pumped circulationand drainage of liquid refrigerant. During a second time period, warmvapor phase refrigerant circulates through the ice freezing/dischargingcoils 142 and header assemblies 154 and 156 and melts the ice 152providing a refrigerant condensing function.

In one embodiment, the insulated tank 140 utilized in the system is adouble-walled rotomolded plastic tank with an R13 to R35 insulationvalue in the lid, walls, and bottom of the tank. Since the systemnormally operates in a daily charge and discharge cycle, rather than aweekly cycle, additional insulation values do not significantly improveoverall performance. The insulated tank 140 integrates attachment pointsfor externally mounted refrigerant management components and providesfor egress of refrigeration piping. The tank is filled with water oreutectic material and incorporates an overflow to maintain fluid levelduring expansion of fluids.

The central device within the refrigerant management unit 104 is anaccumulator vessel called the universal refrigerant management vessel orURMV 146. The URMV 146 is on the low-pressure side of the refrigerantcircuitry and performs several functions. The URMV 146 separates liquidand vapor refrigerant during the refrigerant energy storage period andduring the cooling period. The URMV 146 provides a column of liquidrefrigerant during the refrigerant energy storage period that sustainsgravity circulation through the ice freezing/discharging coils 142inside the insulated tank 140. The URMV 146 is also a vapor disengagingvessel and provides for refrigerant storage. The dry suction return 114to the air conditioner unit 102 compressor 110 during the energy storagetime period is provided by an outlet at the top of the URMV vessel 140.The dry suction return 114 is placed in such a way to prevent liquidrefrigerant from being returned to the compressor. A wet suction return124 is provided through an inlet in the top of the URMV 146 forconnection to an evaporator (load heat exchanger 122) during the timeperiod when the refrigerant energy storage system provides cooling.

The first time period is the refrigerant energy storage time period orstoring energy in ice. The output of the compressor 110 is high-pressurerefrigerant vapor that is condensed to high-pressure liquid, (HPL). Avalve (not shown) on the outlet of the refrigerant pump 120 is energizedto close the connection to the load unit 108. High-pressure liquid, issurrounded by low-pressure liquid refrigerant in a second refrigerantvessel that is a combination oil still/surge vessel 116 that isconnected to the low side of the refrigerant system.

During this first time period (energy storage period) the oilstill/surge vessel 116 is an oil still and during the cooling period,the oil still/surge vessel 116 acts as a refrigerant surge vessel.During the energy storage period, an internal heat exchanger, in whichflows high-pressure liquid refrigerant from the air conditioner unit102, keeps all but a small amount of low-pressure liquid refrigerant outof the oil still/surge vessel 116. The refrigerant that is inside thevessel boils at a rate determined by two capillary pipes. One capillaryis the vent capillary 128 that controls the level of refrigerant in theoil still/surge vessel 116. The second, the oil return capillary 148,returns oil-enriched refrigerant to the compressor 110 within the airconditioner unit 102 at a determined rate. The column of liquidrefrigerant in the URMV 146 is acted on by gravity and positioning theoil still/surge vessel 116 near the bottom of the URMV 146 columnmaintains a steady flow of supply liquid refrigerant to the oilstill/surge vessel 116. This vessel is connected to the low-pressureliquid feed line 144 with a P-trap 150 that prevents vapor from enteringthe URMV 146 or the liquid refrigerant pump 120. The surge functionallows excess refrigerant during the cooling period to be drained fromthe ice freezing/discharging coils 142 in the insulated tank 140 keepingthe surface area maximized for condensing refrigerant. Physicalpositioning of the oil still/surge vessel 116 is a factor in itsperformance as a still and as a surge vessel. This oil still/surgevessel 116 additionally provides the path for return of the oil thatmigrates with the refrigerant that must return to the compressor 110.The slightly subcooled (cooler than the vapor-to-liquid phasetemperature of the refrigerant) high-pressure liquid refrigerant thatexits the oil still/surge vessel 116 flows through a mixed phaseregulator 132 (thermodynamic refrigerant vapor trap) where pressure dropoccurs.

As stated above, the refrigerant management unit 104 receiveshigh-pressure liquid refrigerant from the air conditioner unit via ahigh-pressure liquid supply line 112. The high-pressure liquidrefrigerant flows through the heat exchanger within the oil still/surgevessel 116, where it is subcooled, and connects to the mixed phaseregulator 132, where the refrigerant pressure drop takes place. The useof a mixed phase regulator 132 provides many favorable functions besidesliquid refrigerant pressure drop. The mass quantity of refrigerant thatpasses through the mixed phase regulator 132 will match the refrigerantboiling rate in the ice making coils 142 during the energy storage timeperiod. This eliminates the need for a refrigerant level control. Themixed phase regulator 132 passes subcooled liquid refrigerant, butcloses when sensing vapor (or inadequate subcooling of liquid) at itsinlet. The pulsing action of the refrigerant exiting the opening andclosing mixed phase regulator 132 creates a hammer effect upon theliquid refrigerant as a standing wave is produced within the closedcolumn. This agitates the liquid refrigerant in the ice making coils 142during the energy storage time period and enhances heat transfer as wellas assists in segregating liquid and vapor phase refrigerant. The mixedphase regulator 132, in conjunction with the URMV 146, also drains theair conditioner unit 102 of liquid refrigerant keeping its surface areaavailable for condensing. The mixed phase regulator 132 allows headpressure of an air-cooled condensing unit to float with ambienttemperature. The system requires no superheat and no subcooling circuitthat is mandatory with most condensing units connected to a directexpansion refrigeration device.

An adjustment to the mixed phase regulator 132 allows the refrigerantenergy storage and cooling system to make ice with an averagefour-degree approach. The low-pressure liquid refrigerant that leavesthe mixed phase regulator 132 passes through a bifurcator 130 to aneductor (or injector nozzle) located between the inlet to the URMV 146and the upper header assembly 154 of the ice making coils 142 to assistwith gravity refrigerant circulation. The bifurcator 130 reduces thepressure and the flow of the liquid refrigerant. During the refrigerantenergy storage time period, the eductor creates a drop in pressure asthe refrigerant leaves the bifurcator 130 thereby increasing the rate ofrefrigerant circulation in the ice making coils 142 and improving systemperformance.

The mixed phase regulator 132 also varies the flow of refrigerant inresponse to evaporator load. It does this by maintaining a constantpressure in the URMV 146. This allows the condensing pressure to floatwith the ambient air temperature. As the ambient air temperaturedecreases, the head pressure at the compressor 110 decreases. The mixedphase regulator 132 allows liquid refrigerant to pass but shuts downwhen it senses vapor. It holds the dual-phase mixture in a “trap”. Theliquid (being denser) is allowed to pass but starts to close when theless dense gas is passed. The vapor backs up to the condenser 111 tobecome further condensed into a liquid. The mixed phase regulator 132 isself regulating (once calibrated) and has no parasitic losses (adiabaticexpansion). Additionally, the mixed phase regulator 132 improves theefficiency of the heat transfer in the coils of the heat exchanger byremoving vapor out of the liquid and creating a pulsing action on thelow-pressure side. As stated above, the mixed phase regulator 132 opensto let low-pressure liquid through and then closes to trap vapor on thehigh-pressure side and create a pulsing action on the low-pressure sideof the regulator. This pulsing action wets more of the sub-circuitinside wall at the boiling level, which aids in the heat transfer.

The low-pressure liquid enters the URMV 146 vessel and the liquid andvapor components are separated. The liquid component fills the URMV 146to a determined level and the vapor component is returned to thecompressor of the air conditioner unit 102. In a normal direct expansioncooling system, the vapor component circulates throughout the systemreducing efficiency. With this embodiment, the vapor component isreturned to the compressor 110 immediately. The column of liquidrefrigerant in the URMV 146 is acted upon by gravity and has two pathsduring the energy storage time period. One path is to the oilstill/surge vessel 116 where the rate of outflow is metered by capillarytubes 128 and 148. The second path for the column of liquid refrigerantis to the lower header assembly 156, through the ice making coils 142and the upper header assembly 154, and back to the compressor 110through the URMV 146. This gravity circulation in this manner is howenergy is stored in the form of ice when the tank is filled with aphase-change fluid such as water. A solid column of liquid refrigerantin the URMV 146 becomes less dense in the ice making coils 142, as therefrigerant becomes a vapor. This differential maintains the gravitycirculation. Initially vapor, and later in the storage cycle refrigerantliquid and vapor, is returned to the URMV 146. The liquid returns to thecolumn and the vapor returns to the compressor 110 within the airconditioning unit 102. Gravity circulation assures uniform building ofthe ice. As one of the ice making coils 142 builds more ice, its heatflux rate is reduced. The coil next to it now receives more refrigerantuntil it has an equal heat flux rate.

The design of the ice making coils 142 creates an ice build pattern thatkeeps the compressor suction pressure high during the ice build storagetime period. During the final phase of the energy storage time period, arapid formation of ice is built and the suction pressure dropsdramatically. This is the full charge indication that automaticallyshuts off the condensing unit with an adjustable refrigerant pressureswitch.

When the air conditioning unit 102 turns on during the energy storagetime period, high-pressure liquid refrigerant forces the slide (piston)in the pressure operated slide valve to block the free flow ofrefrigerant to the load heat exchanger 122. When the energy storagesystem is fully charged and the air conditioning unit 102 shuts off, themixed phase regulator 132 allows the refrigerant system pressures toequalize quickly. With the high-pressure liquid no longer pushing theslide closed, a spring returns the slide to the open position, allowingrefrigerant to flow to the load heat exchanger 122 without restriction.In one embodiment, the load heat exchanger 122 is located below theenergy storage system, and refrigerant flows by gravity to the floodedevaporator and operates as a thermosiphon.

In summary, when the tank is filled with water and refrigerant iscirculated through the coils, the coils act as an evaporator, formingice and storing energy during one time period. During a second timeperiod, refrigerant circulates through the coils and melts the iceproviding a refrigerant condensing function. This energy storage anddischarge methodology is know as ice-on-coil, inside-melt. The timeperiods are determined by the end-user, a utility, or optional smartcontrols incorporated within or attached to the system.

The disclosed embodiment provides an efficient, refrigeration apparatusthat provides refrigerant based energy storage and cooling. Whenconnected to a condensing unit, the system has the ability to storeenergy capacity during one time period and provide cooling from thestored energy during a second time period. The system requires minimalenergy to operate during either time period, and only a fraction of theenergy required to operate the system during the first time period isrequired to operate the system during the second time period using anoptional refrigerant pump.

FIG. 2 illustrates an embodiment of a high efficiency refrigerant coldstorage and cooling system in a configuration for air conditioning withmultiple evaporators (which includes mini-split systems very common inEurope and the Far East). As shown in FIG. 2, various efficiency optionscan be added to the refrigerant cold storage and cooling system. Aspreviously noted, a liquid refrigerant pump 120 within the refrigerantmanagement unit 104 can be added downstream of the pressure operatedslide valve 118 to circulate refrigerant to a load which is depicted asmini-split evaporators 160 in this embodiment. The coils of the heatexchangers within the mini-split evaporators 160 are fed refrigerantdirectly using liquid overfeed technology. In the wet suction returnline 124, both liquid and vapor return to the energy storage unit 106.The vapor is condensed by discharge coils 142 within the ice 152 and theliquid refrigerant is returned to the inlet of the liquid refrigerantpump 120. Excess refrigerant that may have been utilized during theenergy storage time period is now stored in the oil still/surge vessel116. The refrigerant path options presented with the pressure operatedslide valve in FIG. 2 allow both the air conditioner unit 102 and theenergy storage unit 106 to provide condensing for the mini-splitevaporators 160 within the load unit 108. This is called the “Push” modeand it operates during a third time period.

The pluralities of coils that comprise the ice freezing/discharge coils142 may have a passive water destratification system consisting ofpassive destratifier pipes 164 in physical contact with the icefreezing/discharge coils 142 that provide a path for water displacementoutside the ice boundary. These passive destratifier pipes 164, alongwith stays that keep the coils properly spaced provide mechanicalprotection for the coils during shipment. An optional air bubbler, waterpump, agitator, circulator or the like can be installed to activelydestratify the fluid promoting flow in either direction. Passivedestratifier fins 162 may also be used on the upper header assembly 154,the lower header assembly 156 or other heat exchange surfaces within theenergy storage unit 106 to provide additional destratification and heatexchange within the fluid/ice 152.

The pluralities of coils may also have a passive water destratificationsystem consisting of pipes in physical contact with the coils thatprovide a path for water displacement outside the ice boundary. Thesepipes, along with stays that keep the coils properly spaced, providemechanical protection for the coils during shipment. An optional airbubbler, water pump, agitator, circulator or the like can be installedto actively destratify the fluid promoting flow in either direction.

FIG. 3 is a table illustrating the component status for an embodiment ofa high efficiency refrigerant cold storage and cooling system operatingin three time periods and modes. As shown in FIG. 3, the status of theair conditioner unit 102, the oil still/surge vessel 116, the icefreezing/discharge coils 142 and the pressure operated slide valve 118is depicted for each of the three time periods and modes described. Forexample, in time period 1, during the refrigerant cold storage mode, theair conditioner unit 102 is on, the oil still/surge vessel 116 isoperating as an oil still, the ice freezing/discharge coils 142 aremaking ice with refrigerant flowing from bottom to top, and the pressureoperated slide valve 118 is closed.

During this ice-make (charge) cycle, the air conditioner unit 102supplies hot liquid refrigerant to the system. The circuit follows thepath starting with high-pressure liquid from the condenser 111, throughthe mixed phase regulator 132 (float) that changes the refrigerant to alow-pressure liquid where it is fed into the URMV 146. The system feedslow temperature liquid to the lower header assembly 156 of the heatexchanger within the energy storage unit 106 where it gradually freezesmost of the water in the insulated tank 140. Vapor phase refrigerantexits the upper header assembly and flows back into the URMV 146. Anycarryover liquid falls to the bottom of the URMV 146 and repeats thecircuit through the ice freezing/discharge coils 142. The resulting“dry” low-pressure vapor exits the URMV 146 and the cycle starts again.

In time period 2, during the cooling mode also referred to as thecooling or ice melt (discharge) cycle, the air conditioner unit 102 isoff, the oil still/surge vessel 116 is operating as a surge vessel, theice freezing/discharge coils 142 are condensing with refrigerant flowingfrom top to bottom, and the refrigerant pump 120 and the pressureoperated slide valve 18 are open.

During peak energy periods, the air conditioner unit 102 connected tothe system is turned off and the system discharges the ice createdduring the ice-make cycle. The system discharges the energy sinkprovided by the ice to enable cooling. In the disclosed embodimentsthere are two methods of cooling cycle supported by the system module:load-shifting and load-leveling. Load-shifting makes use of a singlerefrigeration circuit—the system connected to a standard evaporator coilto provide both sensible and latent cooling. The load-leveling mode usestwo separate refrigeration circuits to provide cooling: asensible-evaporator circuit to provide sensible cooling (removing theheat from ventilation air); and, a separate ice-evaporator to providelatent cooling (removing the humidity). A standard air conditioner unit102 and oversized evaporator coil (load unit 108) comprise thesensible-evaporator circuit while the second evaporator coil and theenergy storage unit 106 comprise the ice-evaporator circuit. The reversecan also be accomplished in other embodiments of the load levelingsystem.

The refrigeration circuit in load-shifting mode and the ice-evaporatorcircuit in the load-leveling mode are fundamentally similar with bothsystems being connected to an evaporator coil (load unit 108). Thedifference between the two is that in load-shifting mode, the load unit108 provides both sensible and latent cooling whereas in load-leveling,the load unit 108 provides mainly latent cooling. This allows the samebasic coil design the ability to perform different functions in multipleconfigurations.

During the ice melt cycle, the refrigerant pump 120 is the driving forcefor the refrigerant to the load unit 108. A unique aspect of thesesystems compared to standard air-conditioning systems is that the indoorunit (air handler and load unit 108) can be as far as 150 ft from theenergy storage unit 106 (normal is 80 ft max). This is possible becausethe oil still/surge vessel 116 acts as a liquid receiver and adjusts forthe additional refrigerant liquid required to traverse long lines.Standard air-conditioning systems would starve of liquid at suchdistances and provide poor performance. This enables the disclosedsystems to be applied to much larger building than standard split systemair-conditioners.

One primary application for these types of refrigeration apparatus is inthe field of load shifting peak power demands of daytime airconditioning. There are primarily two methods commonly followed to avoidhigh electrical demand during peak summer hours. One method is calledload shedding in which compressors are shut down during peak periods andcooling is supplied by stored energy such as ice to provide cooling. Theother practice is called load leveling in which a smaller compressor isoperated continuously. During periods of low cooling demand, energy isstored thermally as ice and during periods of moderate demand, the smallcompressor unit matches the load requirement. During periods of highdemand when the small compressor cannot supply the needed energy, thecapacity of the system is supplemented by the melting of ice to make upthe difference. The ice freezing period during low air conditioningdemand may be as long as 12-14 hours, contrasting to the peak demandperiod which may be as short as 3 hours or as long as 10 hours.

The following describes refrigerant flow for both the load-shifting modeand the ice-evaporator circuit in the load-leveling mode. During the icemelt (discharge) cycle, the ice freezing/discharge coils in the energystorage unit 106 act like condensers, taking vapor refrigerant from theload unit 108 and condensing it. The cold liquid refrigerant (32° F.-58°F.) is circulated to the load unit 108 via a liquid refrigerant pump120. If the load unit 108 is sufficiently close to and below therefrigeration management unit 106, the cycle could operate entirely ondensity differences (as a thermosiphon), thereby eliminated the need forthe liquid refrigerant pump 120, and hence reducing energy consumption(increasing system efficiency). This circuit uses only low-pressureliquid and vapor refrigerant.

The steps in the ice-evaporation circuit are:

-   -   1. Liquid refrigerant is pumped out of the URMV 146 via the        liquid refrigerant pump 120 to the load unit 108    -   2. Liquid refrigerant is boiled off in the load unit 108.    -   3. A mixture of vapor and liquid returns from the load unit 108        to the URMV 146 through the wet suction return 124.    -   4. The liquid refrigerant falls to the bottom of the URMV 146.    -   5. Most of the vapor refrigerant component does not enter the        URMV 146, but enters the heat exchanger in the energy storage        unit 106 due to the suction pressure caused by condensing        refrigerant in the refrigeration sub-circuits (coils)    -   6. Vapor refrigerant enters the ice freezing/discharge coils 142        and condenses into a liquid at the lower header assembly 156    -   7. The liquid refrigerant exits the lower header assembly 156        and collects in the bottom of the URMV 146    -   8. The cycle repeats.

In load-shifting mode, the thermal energy unit 106 is the only coolingsystem using energy during prescribed peak times. Therefore, a majorityof the energy use (up to 100%) can be shifted to other non-peak times.The purpose of the load-shifting function is to shift electrical demandto non-peak hours. Total demand is reduced, efficiency is increasedbecause the air conditioning unit operates at a lower ambienttemperature, and demand is shifted from peak hours to non-peak hours.

In the load-leveling mode, two separate refrigeration circuits are usedto provide cooling. The first circuit provides is fed by other coolingsystems and would preferably provide sensible cooling. The disclosedembodiments are used a part of the second refrigeration circuit, theice-evaporator circuit. The disclosed systems provides very efficientlatent cooling because they run much lower temperature (lower pressure)refrigerant thru the load unit 108 compared to most standardair-conditioning systems. The lower resultant dewpoint brings moremoisture (latent energy) out of the air. Use of the system inload-leveling mode to provide the latent cooling enables the size of asensible-only air conditioning system to be reduced. Smallerair-handling systems are also possible. Ideally, the goal is toeliminate dehumidification (latent cooling) on the first coil, andprovide it entirely on the second coil. By improving the efficiency ofthe first refrigeration circuit and using the system to supply thecooling to the second circuit, peak demand may be reduced and overallefficiency may be improved (compared to conventional unitaryair-conditioning system) depending on the cooling demand.

In the load-leveling configuration, the system can still provide thetotal cooling load during shoulder or winter months when the coolingload is minimal or defined by an energy management system to furtherminimize peak electrical demand.

Finally, in time period 3, during the “Push” mode, the air conditionerunit 102 is on, the oil still/surge vessel 116 is acting as acombination oil still and surge vessel, the ice freezing/discharge coils142 are condensing with refrigerant flowing from top to bottom, and therefrigerant pump 120 and pressure operated slide valve 118 are open. The“Push” mode allows the compressor 110 associated with the system (tomake ice) to provide cooling directly to load unit 108. This might serveany number of purposes such as: providing cooling after ice isexhausted; providing additional capacity at peak times (along with theice); and, saving ice for later, presumably for improved cost savings.

Nominally, the timing of an ice build is calculated to address energycosts alone—e.g., the price per kWh. However, the calculation can alsoaddress the efficiency of the system at various times of night, whichindirectly impacts the total energy costs. Nighttime efficiency varieswith ambient temperatures and weather conditions. Nighttime temperaturestypically follow a profile (of being coldest just before sunrise), andthis can be used to optimize build times. However, weather forecasts andother feed forward mechanisms can also be used to optimize build time.The optimization on build-time can consider a number of additionalconstraints and factors as well, such as noise, convenience, maximumconsumption thresholds, etc.

Ice build can also be optimized around expected cooling needs. i.e., itmay be advantageous economically to not build ice if calculations orrules indicate it will not be needed (for the next cycle, or some periodof time). The system need not only be configured to cool a facility,i.e., human comfort. It can provide cooling for any purpose, such ascooling another liquid in a process. The delivered capacity (rate) canbe also adjusted via a valve that feeds some of the output (from liquidrefrigerant pump 120, e.g.) directly back into the system, bypassingevaporator or load unit 108.

The system generates its own water from condensation, and in sufficientquantity to not require the insulated tank 140 to be refilled due toevaporation. The excess water generated through condensation may bedrained through a tube leading from an elevation above the ice to theground. To prevent this pathway from becoming a source of hot air flowinto the tank, a water trap or other valve system can be placed in thetube.

The block of ice 152 formed within the insulated tank 140 is designed tomelt from the top to the bottom (due to refrigerant evaporation) andfrom the inside of each if the ice freezing/discharge coils 142 sectionof ice to the outside (the ice touching the coil melts first). After allthe ice touching the ice freezing/discharge coils 142 has melted,water—not ice—is in contact with the coil, although a “sheath” of watermay be trapped at the top or bottom. This sheath of slows the heattransfer rate from coil to ice. Efficiency and operating conditions areimproved by circulating water through the sheath. To affect such a flow,two things must be accomplished: a complete pathway must be createdalong the ice freezing/discharge coils 142, from open water to openwater, and a means for promoting flow must be established. To create apathway, passive destratifier pipes 164 (thermal conductors such ascopper pipe) are installed towards the bottom of the coil assembly, andphysically bound to each ice freezing/discharge coil 142 along theconductor's length. Furthermore, the passive destratifier pipe 164extends out beyond the ice build area into open water. Multiple suchconductors may be added. Each conductor thus creates its own “sheath” ofwater which starts in open water and connects to each coil's sheath,thereby creating a pathway from the bottom up. At the top of each coil,a passive destratifier pipe 164 is again added to create another sheaththat extends through the ice on the top. This conductor may be of adifferent design, such as four stems that extend up from the headers, orperhaps a thin conductive fin that runs the full length of each coilassembly. This method is optimized if the ice block is built with thewater level in the tank such that at full build time, there is openwater above the ice. (Water level rises substantially during build dueto the lower density of ice, so the water level need not start above thecoil assembly.) Having thus established a path of water from open water,to each coil, and out the top of the ice block, the issue of promotingwater flow is addressed. Passive and active methods can both be applied.A passive method would use the stratification in temperature and densityto create a natural flow. Active systems would stimulate the flowfurther by introducing water bubbles in the tank, or up each coil, or bypumping water to create circulation.

FIG. 4 illustrates another embodiment of refrigeration apparatus used asa cold storage and cooling system using a solenoid valve 166. Thesolenoid valve 166 is designed to replace the pressure operates slidevalve 118 of FIG. 1 and is open during the ice melt cycle and is closedduring the ice make cycle. When a pressure operated slide valve is used,during the ice make cycle, the pressure in the high-pressure liquidsupply line 112 from the compressor discharge is high and overcomes thespring force within the pressure operated slide valve 118. The pistonwithin the valve is then at its farthest position which closes the inletline to the liquid refrigerant pump 120 and prevents flow of liquid.During the ice melt cycle, the pressure on the high-pressure liquidsupply line 112 is lower and the piston is at its nearest position. Atthis condition, both the inlet and the outlet to the valve are open andthe refrigerant flows to the liquid refrigerant pump 120 and onward tothe load unit 108 as shown in FIG. 1.

By removing the pressure operated slide valve 118 and the direct accessline from the high-pressure liquid supply line 112, refrigerant canalways flow from the URMV 146 to the liquid refrigerant pump 120, butflow is regulated by a solenoid valve 166 (in this embodiment downstreamof the liquid refrigerant pump). This configuration allows the use ofoff-the-shelf valves and greater precision and control of flow withelectronic relay based controllers instead of relying upon pressureswitches to regulate flows. In an embodiment as detailed in FIG. 4, theentire control of the refrigeration apparatus may be controlled by arefrigerant management controller 168 that is in communication with therefrigeration management unit 104 and used to control the operation ofthe system. The refrigerant management controller 168 may be driven by aPC type board, IC chip incorporated in a form such as a programmablelogic controller (PLC) or programmable microcontroller with analog,digital and relay inputs and outputs. This greatly increases theflexibility of the system and reduces cost of manufacture while allowingnumerous additional applications and “smart controls” for the apparatus.

The refrigerant management controller 168 may receive real-time data andenvironmental information from communications with environmental sensors172. These environmental sensors 172 may measure; climatic variablessuch as time, temperature, humidity (dewpoint), UV index, air qualityindex, climate zone; condition/consumption variables such as powerconsumption, energy grid status, energy demand, energy consumption,cooling degree days, utility load profiles; and/or, cost variables suchas power costs, electric power price, time dependent value of energy,oil price, propane price, natural gas price, day-ahead price, day-ofprice, electricity generation price, electricity transmission price,electricity distribution price, electric utility revenue or energyservice company revenue, or a variety of other variables that might beuseful in determining how and when the refrigeration apparatus shouldperform in response to a price event, a reliability event, or a loadbalancing event for example. These factors may change times, rates andspecific performance issues in the ice make cycle that might optimizeperformance or other factors such as when noise from the unit may be aconcern. The refrigerant management controller 168 may also contain adata collection unit 170 in which historical environmental andperformance may be stored. This data could be used by an outside person(i.e., utility company, energy suppliers, energy service company, demandresponse aggregator, system operator or the like) or by the refrigerantmanagement controller 168 to make performance changes to one or manyunits based upon historical data of the unit.

Additional communications with the refrigerant management controller 168can be accomplished with a communications device 174 that wouldfacilitate either a wireless link 176 or a hardwire link (i.e., externalphysical network interface or expansion interface) to a telecom 180 ornetwork/internet (i.e., wide area network, wide area communicationsinterface, radio broadcast data system, paging system or the like). Inthis way, collected historical data may be downloaded from the system orspecific control functions may be programmed into the device such asweather data and forecasts, solar tables and the like. External controlinputs or data can also be communicated to refrigerant managementcontroller 168 based on current, typical, or predicted conditions beyondthe direct sensing ability of controller 168, such as regional energysupply, cost, or consumption data. The historic data (either captured bythe controller or externally derived), environmental data (past, presentor forecast), weather, energy, cost, or other data which significantlyimpacts the efficiency or desired performance and optimization ofmake/melt times can be used to provide great optimization of performanceof the apparatus in a multitude of application environments.

In these disclosed embodiments, a wide variety of heat loadsapplications can be adapted in conjunction with the aforementionedembodiments. Essentially any cooling need that can be transferred viarefrigerant piping may be utilized with these systems. For example,dairy cooling, plastic injection molding cooling, fresh catch fishrefrigeration, inlet cooling for turbine power generation, watercraftrefrigeration and air conditioning as well as a wide variety of processcooling applications or the like can benefit from these types ofsystems.

1. A refrigeration apparatus comprising: a condensing unit comprising acompressor and a condenser; a thermal energy storage unit comprising atank that contains a storage heat exchanger and at least partiallyfilled with a phase change liquid; a load heat exchanger; arefrigeration management unit connected to said condensing unit, saidthermal energy storage unit and said load heat exchanger; and, arefrigerant management controller in communication with saidrefrigeration management unit and comprised of operational controllersusing environmental data to regulate and control operation of saidrefrigeration apparatus.
 2. A refrigeration apparatus of claim 1,wherein said refrigerant management controller is located in proximityto said thermal energy storage unit.
 3. A refrigeration apparatus ofclaim 1, wherein said refrigerant management controller is locatedremotely from said thermal energy storage unit.
 4. A refrigerationapparatus of claim 1, wherein said refrigerant management controllercontrols a plurality of said refrigerant management units of a pluralityof said thermal energy storage units.
 5. A refrigeration apparatus ofclaim 1, wherein said refrigerant management controller is controlled bya utility company.
 6. A refrigeration apparatus of claim 1, wherein saidrefrigerant management controller is controlled by an energy servicecompany.
 7. A refrigeration apparatus of claim 1, wherein saidrefrigerant management controller is controlled by a demand responseaggregator.
 8. A refrigeration apparatus of claim 1, wherein saidenvironmental data consists of at least one of the following real-timeenvironmental variables: time, temperature, relative humidity, dewpoint,UV index, air quality index and climate zone.
 9. A refrigerationapparatus of claim 1, wherein said environmental data consists of atleast one of the following real-time environmental variables: powerconsumption, energy demand, energy consumption, cooling degree days,utility load profiles, and energy grid status.
 10. A refrigerationapparatus of claim 1, wherein said environmental data consists of atleast one of the following real-time environmental variables: currentelectric power price, current oil price, current propane price, currentnatural gas price, day-ahead price, day-of price, electric utilityrevenue or energy service company revenue.
 11. A refrigeration apparatusof claim 1, wherein said environmental data consists of at least one ofthe following projected environmental variables: projected temperature,projected relative humidity, projected dewpoint, projected UV index andprojected air quality index.
 12. A refrigeration apparatus of claim 1,wherein said environmental data consists of at least one of thefollowing projected environmental variables: projected powerconsumption, projected energy demand, projected energy consumption,projected cooling degree days, projected utility load profiles, andprojected energy grid status.
 13. A refrigeration apparatus of claim 1,wherein said environmental data consists of at least one of thefollowing projected environmental variables: projected electric powerprice, projected oil price, projected propane price, projected naturalgas price, projected day-ahead price, projected day-of price electricrate forecast and projected electric utility revenue.
 14. Arefrigeration apparatus of claim 1, wherein said environmental data isderived at the location of said thermal energy storage unit.
 15. Arefrigeration apparatus of claim 1, wherein said environmental data isderived at a location remote from said thermal energy storage unit andtransmitted to said refrigerant management controller of said thermalenergy storage unit.
 16. A refrigeration apparatus of claim 1, whereinsaid environmental data is sensed using sensors from a plurality ofthermal energy storage units.
 17. A refrigeration apparatus of claim 1,wherein said environmental data comprises at least one of the following:electricity generation price, electricity transmission price andelectricity distribution price.
 18. A refrigeration apparatus of claim1, wherein at least a portion of said regulation and control operationof said refrigeration apparatus is based upon a time dependent value ofenergy.
 19. A refrigeration apparatus of claim 1, wherein at least aportion of said regulation and control operation of said refrigerationapparatus is based upon at least one of the following: electricitygeneration price, electricity transmission price or electricitydistribution price.
 20. A refrigeration apparatus of claim 1, wherein atleast a portion of said regulation and control operation of saidrefrigeration apparatus is in response to a price event, a reliabilityevent, or a load balancing event.
 21. A refrigeration apparatus of claim1, wherein said transmission of said environmental data is performedwith a wide area communications interface
 22. A refrigeration apparatusof claim 21, wherein said wide area communications interface is a radiobroadcast data system
 23. A refrigeration apparatus of claim 21, whereinsaid wide area communications interface is a paging system
 24. Arefrigeration apparatus of claim 21, wherein said wide areacommunications interface is an external physical network interface
 25. Arefrigeration apparatus of claim 21, wherein said wide areacommunications interface further comprises an expansion interface, saidexpansion interface that is used to extend the communicationcapabilities of said refrigerant management controller and provide meansfor memory storage and logging.